1. Technical Field
One or more aspects of the invention relate to image forming apparatus that form an image using toner by an electrophotographic method, and more specifically, image forming apparatus that determine toner condition based on toner transfer condition.
2. Description of Related Art
In a known electrophotographic image forming apparatus, insufficiently-charged toner may appear due to toner deterioration. The insufficiently-charged toner may move from a photosensitive member to a transfer member, e.g., a conveyor belt, in an unintended area, and thus make one or both of the transfer member and a sheet dirty. To prevent this problem, a known image forming apparatus determines toner condition. When the image forming apparatus determines that toner is in the deteriorated condition, the image forming apparatus provides notification that a developing unit, which stores the deteriorated toner, needs to be replaced.
In a known technique for determining the toner condition, an image forming apparatus includes a sensor that detects a surface condition of photosensitive belt. The image forming apparatus determines the toner condition based on an amount of reflected light from the intermediate transfer belt.